X-ray Computed Tomography (CT) is in wide use at the present time in the medical field for medical imaging. The use of CT produces a cross sectional image from a plurality of attenuation measurements taken at a plurality of angles around the object. However, none of the medical derived CT systems have been designed to meet the real-time inspection requirements for industrial applications. Such systems require an extensive time frame to accomplish scanning, acquire data and provide an image therefrom.
Attempts have been made to provide improved CT systems for nonmedical use. One such system employs an X-ray unit to pre-scan an object, and the pre-scan data is used to select locations for subsequent CT scanning. This system, which is illustrated by U.S. Pat. No. 5,367,552 to Peschmann, uses a rotating CT scanning unit which requires an object to remain stationary during scanning.
In an attempt to improve tomographic reconstruction imaging, algebraic reconstruction techniques (ART) have been employed, but known ART systems have many shortcomings in providing high quality reconstructed imagery. U.S. Pat. No. 5,442,672 to Bjorkholm et al. discloses a three-dimensioned reconstruction based upon a limited number of X-ray projections where algebraic reconstruction techniques are used to reconstruct an image from projected images.